The present invention relates to thermal and stress mapping of a body lumen, and more particularly to analyzing the material strain and color of the surface of a lesion molding balloon to classify the type of lesion and whether it is vulnerable to rupture.
It is widely recognized that plaques or lesions can be classified into three broad categories: calcified or hard plaque lesions, fibrous or soft lesions and inflamed soft lipid filled plaques or lesions. The diagnosis of the type of lesion drives the particular treatment of the lesion, whether it is removal of the lesion by rotablator, predilatation by balloon angioplasty, delivery of a stent, with or without predilatation, or the like.
In particular, the identification of inflamed plaques or lesions is important since these lesions are at greatest risk of rupture, which can lead to a large thrombus or blood clot, which can completely occlude the flow of blood through the artery, leading to injury of the heart or brain. An inflamed or vulnerable lesion is characterized by its cap thickness, lipid pool size and inflammation or temperature. This is discussed in great detail in WO 97/10748 published Mar. 27, 1997 and entitled "Detecting Thermal Discrepancies In Vessel Walls", the entire contents of which are hereby incorporated by reference. As discussed in the published PCT application, considerable evidence indicates that plaque rupture triggers 60-70% of fatal myocardial infarctions. As is well known in the art, and described in the published PCT application, an inflamed plaque is hotter than the surrounding tissue. This published PCT patent application relates to using an infrared fiberoptic system to locate inflamed heat producing plaque. However, the device described in this PCT published application is very expensive, making it available in a limited number of procedures. What is needed is a more inexpensive method for classifying plaques or lesions, and in particular determining which plaques are hard, soft or inflamed, which drives the treatment after diagnosis.